package leetcode.code0796;

import leetcode.IDebug;

public class Solution1 implements IDebug {

	public boolean rotateString(String s, String goal) {
		if (s.length() != goal.length()) {
			return false;
		}
		return this.strStr(s + s, goal) != -1;
	}

	public int strStr(String haystack, String needle) {
		char[] chars1 = haystack.toCharArray();
		char[] chars2 = needle.toCharArray();
		int len1 = chars1.length;
		int len2 = chars2.length;
		int[] p = new int[len2];
		// p中m位置记录数值n,表示[0,n-1]的字符串同[m-n+1,m]字符串相同
		for (int i = 1, j = 0; i < len2 && j < len2; i++) {
			while (j > 0 && chars2[j] != chars2[i]) {
				j = p[j - 1];
			}
			if (chars2[i] == chars2[j]) {
				j++;
			}
			p[i] = j;
		}
		for (int i = 0, j = 0; i < len1 && j < len2; i++) {
			while (j > 0 && chars2[j] != chars1[i]) {
				j = p[j - 1];
			}
			if (chars2[j] == chars1[i]) {
				j++;
			}
			if (j == len2) {
				return i - j + 1;// i-(j-1)
			}
		}
		return len2 == 0 ? 0 : -1;// 当 needle 是空字符串时我们应当返回 0
	}

	@Override
	public void debug4() {
		// TODO Auto-generated method stub

	}

	@Override
	public void debug3() {
		// TODO Auto-generated method stub

	}

	@Override
	public void debug2() {
		// TODO Auto-generated method stub

	}

	@Override
	public void debug1() {
		// TODO Auto-generated method stub

	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub

	}

}
